Crank Stiffness Tests???

hi, anyone know of any good crank stiffness tests out there that have
been done to compare newer road cranks? with all these light weight
carbon models coming out i'd be interested to see how stiff they are.
thanks!

wrote:
hi, anyone know of any good crank stiffness tests out there that have
been done to compare newer road cranks? with all these light weight
carbon models coming out i'd be interested to see how stiff they are.
thanks!

Velonews did some tests in late 2003 and found that the new Dura ace
cranks were by far the stiffest. The carbon cranks were fine though, as
far as stiffness is concerned.

A French magazine tested a bunch of cranks in 2004, and found that the
FSA Energy cranks (fat hollow aluminum) were the stiffest.

The stiffness of carbon cranks varies a lot depending on the design...
but does stiffness even matter? I doubt that there is a perceptible
difference in feel or performance. I'd be more concerned about
durability... and I've seen no published tests for that.

wrote:
hi, anyone know of any good crank stiffness tests out there that have
been done to compare newer road cranks? with all these light weight
carbon models coming out i'd be interested to see how stiff they are.
thanks!

Try to remember that crank and BB stiffness tests were accomplished by
a gorilla machine that exerted FAR more force than the mere human can,
even greater than big boy sprinters like mario, and Chalo...

If they used forces like those exerted by the average, 45 yr old
cyclist, then the results would have been inconclusive and not able to
be used by the marketeers.

Qui si parla Campagnolo wrote:
wrote:

hi, anyone know of any good crank stiffness tests out there that have
been done to compare newer road cranks? with all these light weight
carbon models coming out i'd be interested to see how stiff they are.
thanks!


Try to remember that crank and BB stiffness tests were accomplished by
a gorilla machine that exerted FAR more force than the mere human can,

peter, with respect, those machines exert forces in the same range as
humans. the only reason machines are used is so that the tests are
controlled & repeatable. and this is not an accelerated fatigue test,
just deflection. deflection with just one pound of force is measurable,
so the relative difference between cranks can be gauged - and that's the
objective.

even greater than big boy sprinters like mario, and Chalo...

If they used forces like those exerted by the average, 45 yr old
cyclist, then the results would have been inconclusive and not able to
be used by the marketeers.

well, i weigh 205, and when i'm climbing, there is undoubtedly a
substantial difference between my old solid armed suntour superbe pro
and my dura-ace hollowtech cranks. does it stop me getting up the hill?
no, of course not. but is it nicer to ride? absolutely. you bantam
weights are lucky you never get to experience the difference. noodles
are not much fun.

Dans le message de
oups.com,
Qui si parla Campagnolo a réfléchi, et puis a déclaré :
wrote:
hi, anyone know of any good crank stiffness tests out there that have
been done to compare newer road cranks? with all these light weight
carbon models coming out i'd be interested to see how stiff they are.
thanks!

Try to remember that crank and BB stiffness tests were accomplished by
a gorilla machine that exerted FAR more force than the mere human can,
even greater than big boy sprinters like mario, and Chalo...

Gee, Peter, I am trying to remember. I had to look it up. The figures I
quoted from Le Cycle magazine's test were far from extraordinary. I wonder
where your tests were published, so I could get a look at them. You didn't
make that statement up, by any chance ???

If they used forces like those exerted by the average, 45 yr old
cyclist, then the results would have been inconclusive and not able to
be used by the marketeers.

So I guess you're saying that *any* crank is good enough. Even cranks from
The Republic ?

On another front - I just got a pair of Aksiums (Mavic's new cheapo wheels)
for winter use, and they have around 1000 km on them already. Excellent
wheels, IMHO. What would you have cooked up for me for the price of 160
euros ?? Yes, bought at the local store, not by mail or e-mail.
--
Sandy
Verneuil-sur-Seine
*******

La vie, c'est comme une bicyclette,
il faut avancer pour ne pas perdre l'équilibre.
-- Einstein, A.

I'd find it hard to believe that there is no measureable difference,
many of them are totally different in construction. Kind of like most
bike frames are similar in shape, but they all sure aren't similar in
stiffness! Anyone know of a web link or anything at all that has
published numbers from a legitimate test? I think if we had one to
look at, we could figure out how much of a performance difference
that's going to have. Even a tiny amount of difference might add up to
quite a bunch of seconds in something like a climb or time
trial..........wonder if Shimano has numbers anywhere on their 9spd vs.
10spd cranks??????

Peter Chisholm writes:

Hi, anyone know of any good crank stiffness tests out there that
have been done to compare newer road cranks? With all these light
weight carbon models coming out I'd be interested to see how stiff
they are.

Try to remember that crank and BB stiffness tests were accomplished
by a gorilla machine that exerted FAR more force than the mere human
can, even greater than big boy sprinters like Mario, and Chalo...

If they used forces like those exerted by the average, 45 yr old
cyclist, then the results would have been inconclusive and not able
to be used by the marketeers.

I take it this is in the line of frame flex and lost energy. Don't
worry about crank stiffness, worry about crank failure, which can be a
fatal flaw. If a left crank breaks while pedaling in the standing
position adjacent to a ready-mix truck, for instance, the rider WILL
take a dive under the wheels of that truck if he is not lucky enough
to crash into its tires which is also not a benign collision.

Crank manufacturers are not addressing the principal failure modes of
current cranks, which are in bending crosswise to the bicycle and that
occur at the bottom of the stroke and especially the breakout of pedal
eyes. Besides that, Campagnolo is still finishing their Record cranks
with a, more than cosmetic, milky anodizing that causes crack
initiation.

Jobst Brandt

On Wed, 19 Oct 2005 18:20:04 +0000, jobst.brandt wrote:

Don't
worry about crank stiffness, worry about crank failure, which can be a
fatal flaw. If a left crank breaks while pedaling in the standing
position adjacent to a ready-mix truck, for instance, the rider WILL
take a dive under the wheels of that truck if he is not lucky enough to
crash into its tires which is also not a benign collision.

Crank manufacturers are not addressing the principal failure modes of
current cranks, which are in bending crosswise to the bicycle and that
occur at the bottom of the stroke and especially the breakout of pedal
eyes. Besides that, Campagnolo is still finishing their Record cranks
with a, more than cosmetic, milky anodizing that causes crack
initiation.

Well, they probably don't get too many complaints -- most people don't
ride anywhere near the number of miles it takes to break a crank. Those
who do are likely to be sponsored riders who get new equipment all the
time anyway.

Note that these days one can buy a whole new crank w/ chainrings, on sale,
for less than the cost of replacement chainrings from a bike shop. An
engineer from a large bike company once said to me, "it's probably better
that way." (Actually he was even more concerned about BB spindles, and
thus pro-cartridge.) And no, I ain't tellin' who.

So of course you're right, but I can't believe you really think they'd
ever admit it. I know you weren't born yesterday. Maybe it's wishful,
"thinking out loud," but still...

Matt O.

Jobst states:

Besides that, Campagnolo is still finishing their Record cranks
with a, more than cosmetic, milky anodizing that causes crack
initiation

When you state "cosmetic, milky anodizing", may I presum you speaking
of Campagnolo's aluminum cranks, not the carbon cranks. Does this same
this same anodizing appear on other Campy cranks like the Centaur and
Veloce aluminum crank like he

http://www.yellowjersey.org/CENCOMPC.JPG

Dans le message de
oups.com,
a réfléchi, et puis a déclaré :
I'd find it hard to believe that there is no measureable difference,
many of them are totally different in construction. Kind of like most
bike frames are similar in shape, but they all sure aren't similar in
stiffness! Anyone know of a web link or anything at all that has
published numbers from a legitimate test? I think if we had one to
look at, we could figure out how much of a performance difference
that's going to have. Even a tiny amount of difference might add up
to quite a bunch of seconds in something like a climb or time
trial..........wonder if Shimano has numbers anywhere on their 9spd
vs. 10spd cranks??????

Mentioned before - it's in PAPER in the magazine Le Cycle.
What they found (not from Shimano, but from testing) was that the Ultegra
10V crankset was MORE rigid than the DuraAce.

You allergic to print ?

I wish I could still worry about chasing seconds, instead of minutes, in
TT's.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR